U.S. patent application number 12/097120 was filed with the patent office on 2009-12-03 for aqueous powder dispersion, which can be cured by radical polymerization, method for the production thereof and their use.
This patent application is currently assigned to BASF COATINGS AG. Invention is credited to Berthold Austrup, Hubert Baumgart, Bostjan Muhic.
Application Number | 20090298997 12/097120 |
Document ID | / |
Family ID | 37682672 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090298997 |
Kind Code |
A1 |
Baumgart; Hubert ; et
al. |
December 3, 2009 |
AQUEOUS POWDER DISPERSION, WHICH CAN BE CURED BY RADICAL
POLYMERIZATION, METHOD FOR THE PRODUCTION THEREOF AND THEIR USE
Abstract
Aqueous, structurally viscous powder dispersions curable by
free-radical polymerization, substantially or entirely free from
volatile organic compounds, and comprising as their disperse phase
solid and/or highly viscous particles (A) which are dimensionally
stable under storage and application conditions and have a z-mean
average particle size as measured by photon correlation
spectroscopy of 80 to 750 nm, the particles (A) comprising at least
one free-radically crosslinkable binder (A1) having a glass
transition temperature of -70 to +50.degree. C., an olefinically
unsaturated double bond content of 2 to 10 eq/kg and an acid group
content of 0.05 to 15 eq/kg, in an amount, based on (A), of 50 to
100% by weight; process for their preparation, and their use.
Inventors: |
Baumgart; Hubert; (Munster,
DE) ; Austrup; Berthold; (Nordkirchen, DE) ;
Muhic; Bostjan; (Ljubljana, SI) |
Correspondence
Address: |
Mary E. Golota;Cantor Colburn LLP
201 W. Big Beaver Road, Suite 1101
Troy
MI
48084
US
|
Assignee: |
BASF COATINGS AG
Munster
DE
|
Family ID: |
37682672 |
Appl. No.: |
12/097120 |
Filed: |
November 9, 2006 |
PCT Filed: |
November 9, 2006 |
PCT NO: |
PCT/EP2006/010718 |
371 Date: |
July 8, 2009 |
Current U.S.
Class: |
524/556 |
Current CPC
Class: |
C08G 18/7837 20130101;
C09D 5/02 20130101; C09D 175/16 20130101; C08G 18/672 20130101;
C09D 5/03 20130101 |
Class at
Publication: |
524/556 |
International
Class: |
C09D 5/03 20060101
C09D005/03 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2005 |
DE |
10 2005 053 663.8 |
Claims
1. An aqueous, structurally viscous powder dispersion, comprising:
particles (A), which are solid, highly viscous, or a combination
thereof are dimensionally stable under storage and application
conditions, have a z-mean average particle size as measured by
photon correlation spectroscopy of 80 to 750 nm, and comprising at
least one free-radically crosslinkable binder (A1) having a glass
transition temperature of -70 to +50.degree. C., an olefinically
unsaturated double bond content of 2 to 10 eq/kg and an acid group
content of 0.05 to 15 eq/kg, in an amount, based on (A), of 50 to
100% by weight, wherein the aqueous, structurally viscous powder
dispersion is substantially or entirely free from volatile organic
compounds, and is curable by free-radical polymerization.
2. The aqueous, structurally viscous powder dispersion of claim 1,
wherein the at least one free-radically crosslinkable binder (A1)
has a number-average molecular weight of 1000 to 50 000
daltons.
3. The aqueous, structurally viscous powder dispersion of claim 1,
wherein the olefinically unsaturated double bonds are in groups
selected from the group consisting of (meth)acrylate, ethacrylate,
crotonate, cinnamate, vinyl ether, vinyl ester, dicyclopentadienyl,
norbornenyl, isoprenyl, isopropenyl, allyl, butenyl,
dicyclopentadienyl ether, norbornenyl ether, isoprenyl ether,
isopropenyl ether, allyl ether butenyl ether, dicyclopentadienyl
ester, norbornenyl ester, isoprenyl ester, isopropenyl ester, allyl
ester, butenyl ester, and a combination thereof.
4. The aqueous structurally viscous powder dispersion of claim 3,
wherein the olefinically unsaturated double bonds are in
(meth)acrylate groups.
5. The aqueous structurally viscous powder dispersion of claim 1,
wherein the at least one free-radically crosslinkable binder (A1)
is selected from the group consisting of oligomeric and polymeric
epoxy(meth)acrylates, urethane (meth)acrylates and carbonate
(meth)acrylates.
6. The aqueous, structurally viscous powder dispersion of claim 5,
wherein the at least one free-radically crosslinkable binder (A1)
is an oligomeric or polymeric urethane (meth)acrylate.
7. The aqueous structurally viscous powder dispersion of claim 1,
wherein the particles (A) have a z-mean average particle size as
measured by photon correlation spectroscopy of 80 to 400 nm.
8. The aqueous, structurally viscous powder dispersion of claim 1,
further comprising at least one additive (A2) selected from the
group consisting of salts which can be decomposed thermally without
residue, salts which can be decomposed thermally substantially
without residue; binders other than the at least one free-radically
crosslinkable binder (A1) and curable physically, thermally or with
actinic radiation; neutralizing agents; thermally curable reactive
diluents; reactive diluents curable with actinic radiation; opaque
color pigments, transparent color pigments, opaque effect pigments,
transparent effect pigments; molecularly dispersely soluble dyes;
opaque fillers, transparent fillers; nanoparticles; light
stabilizers; antioxidants; devolatilizers; wetting agents;
emulsifiers; slip additives; polymerization inhibitors;
free-radical polymerization initiators, photoinitiators;
thermolabile free-radical initiators; adhesion promoters; flow
control agents; film-forming assistants; Theological assistants,
thickeners, structurally viscous sag control agents, flame
retardants; corrosion inhibitors; free-flow aids; waxes;
siccatives; biocides, matting agents, and a combination
thereof.
9. A process for preparing the aqueous, structurally viscous powder
dispersion of claim 1, comprising dispersing the particles (A) in
an aqueous medium (B).
10. The process of claim 9, wherein dispersing the particles (A) in
the aqueous medium (B) comprises: dissolving the at least one
free-radically crosslinkable binders (A1) and, optionally, an
additives (A2) in an organic solvent to produce a solution;
dispersing the solution in water in the presence of a neutralizing
agent to produce a dispersion; diluting the dispersion with water
to produce a water-in-oil emulsion, which is further diluted to
form an oil-in-water emulsion; and removing the organic solvents
from the oil-in-water emulsion.
11. A coating material, adhesive or sealant for producing a coating
adhesive layer or seal comprising the aqueous, structurally viscous
powder dispersion of claim 1.
12. The coating material adhesive or sealant for producing a
coating adhesive layer or seal of claim 11, wherein the coating
material is a primer, priming material, surfacer, basecoat,
solid-color topcoat or clearcoat material for producing single-coat
or multicoat primer coating systems, corrosion control coats,
antistonechip priming coats, surfacer coats, basecoats, solid-color
topcoats or clearcoats.
13. The coating material adhesive or sealant for producing a
coating adhesive layer or seal of claim 12, wherein the clearcoat
material serves for producing single-coat or multicoat clearcoat
systems as part of multicoat color and/or effect paint systems.
14. The coating material adhesive or sealant for producing a
coating adhesive layer or seal of claim 13, wherein the multicoat
color and/or effect paint systems are produced with the aid of
wet-on-wet techniques.
15. The coating material adhesive or sealant for producing a
coating adhesive layer or seal of claim 11, wherein the
free-radical polymerization is initiated and maintained thermally
and/or with actinic radiation.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to new aqueous powder
dispersions curable by free-radical polymerization. The present
invention also relates to a new process for preparing aqueous
powder dispersions curable by free-radical polymerization. The
present invention further relates to the use of the new aqueous
powder dispersions curable by free-radical polymerization and of
the aqueous powder dispersions curable by free-radical
polymerization and prepared by the new process as coating
materials, adhesives, and sealants for producing coatings, adhesive
layers, and seals.
PRIOR ART
[0002] Aqueous powder dispersions, especially aqueous powder
coating dispersions, are also referred to by those in the art,
conventionally, as "powder slurries" or, for short, as
"slurries".
[0003] The term "slurries" here and below refers for the sake of
brevity to powder slurries curable by free-radical
polymerization.
[0004] Free-radical polymerization, conventionally, is carried out
with compounds which contain olefinically unsaturated double bonds.
The free-radical polymerization can be initiated and maintained
thermally or with actinic radiation.
[0005] Actinic radiation here and below means electromagnetic
radiation, such as near infrared (NIR), visible light, UV
radiation, X-radiation or gamma radiation, especially UV radiation,
or particulate radiation, such as electron beams, proton beams,
beta radiation, alpha radiation or neutron beams, especially
electron beams.
[0006] The U.S. Pat. No. 6,432,490 B1 or the corresponding
international patent application WO 02/064267 A2 discloses slurries
which comprise ionically stabilized urethane acrylates having an
unsaturated double bond content or double bond equivalent weight of
0.1 to 10 eq/kg.
[0007] Further details of the ionic stabilization, however, are
lacking, and the examples disclose only a conventional clearcoat
material based on organic solvents and a urethane acrylate which is
free of acid groups.
[0008] Following their application, the known slurries can be cured
with near infrared to give hard, solvent-resistant, and
yellowing-free coatings, especially clearcoats.
[0009] German patent application DE 199 08 013 A1 discloses
structurally viscous slurries whose solid, spherical particles are
found by the laser diffraction method to have an average size of
0.8 to 20 .mu.m and a maximum size of 30 .mu.m.
[0010] The constituents of the known slurries that are curable with
actinic radiation contain ion-forming groups, particularly carboxyl
groups, in an amount of 0.05 to 1 eq/kg, and neutralizing agents in
an amount of 0.05 to 1 eq/kg.
[0011] The known slurries have a viscosity of 50 to 1000 mPas at a
shear rate of 1000 s.sup.-1, 150 to 8000 mPas at a shear rate of 10
s.sup.-1, and 180 to 12 000 mPas at a shear rate of 1 s.sup.-1.
[0012] The examples, however, disclose only a urethane acrylate
having a double bond equivalent weight of 3 eq/kg but containing no
acid groups. It is present in the particles of the slurry in
question in an amount of 41.53% by weight, based on solids.
[0013] Following their application, the known slurries can be cured
with UV radiation to give coatings, especially clearcoats, which
have outstanding appearance, high chemical resistance, a high level
of hardness, and a smooth surface. Even at film thicknesses of 40
to 50 .mu.m they exhibit no pops and are free from mud
cracking.
[0014] Nevertheless, the profile of performance properties of the
known slurries requires constant ongoing development in order to
satisfy the ever-higher requirements of the market. In particular
it is necessary to develop the coatings produced from the known
slurries, especially clearcoats, with regard to their chemical
resistance, stonechip resistance, scratch resistance, and
condensation resistance.
Problem Addressed
[0015] It is an object of the present invention to find new aqueous
powder dispersions curable by free-radical polymerization (and
referred to collectively below as "new slurries") which can be
prepared easily and very reproducibly.
[0016] In the absence of actinic radiation the new slurries ought
to be particularly stable on storage with no propensity to settle
and/or agglomerate. Should any slight sedimentation and/or
agglomeration of particles occur, nevertheless, after a prolonged
period, it ought to be possible to disperse the sedimented
particles again rapidly by brief stirring and to comminute the
agglomerated particles again rapidly.
[0017] The new slurries ought to produce coatings, especially
clearcoats, which have outstanding appearance properties, in
particular a high gloss. They ought to be particularly resistant to
chemicals, condensation, and mechanical exposure, particularly that
from stone impact. They ought additionally to be highly scratch
resistant. Furthermore, they ought effectively to level out
unevennesses in the substrate that show through to the topmost
coating of a multicoat paint system, and so ought to exhibit a
particularly smooth and defect-free surface. In particular,
however, they ought to remain free from pops and mud cracking even
at particularly high film thicknesses of more than 80 .mu.m.
Solution
[0018] Found accordingly have been the new aqueous, structurally
viscous powder dispersions curable by free-radical polymerization,
substantially or entirely free from volatile organic compounds, and
comprising as their disperse phase solid and/or highly viscous
particles (A) which are dimensionally stable under storage and
application conditions and have a z-mean average particle size as
measured by photon correlation spectroscopy of 80 to 750 nm, the
particles (A) comprising at least one free-radically crosslinkable
binder (A1) having a glass transition temperature of -70 to
+50.degree. C., an olefinically unsaturated double bond content of
2 to 10 eq/kg and an acid group content of 0.05 to 15 eq/kg, in an
amount, based on (A), of 50 to 100% by weight.
[0019] The new aqueous, structurally viscous powder dispersions
curable by free-radical polymerization and free substantially or
entirely from volatile organic compounds are referred to below as
"slurries of the invention".
[0020] Also found has been the new process for preparing the
slurries of the invention, which involves dispersing the particles
(A) in an aqueous medium (B), and which is referred to below as
"process of the invention".
[0021] Also found has been the new use of the slurries of the
invention and of the slurries prepared by the process of the
invention, as coating materials, adhesives, and sealants, for
producing coatings, adhesive layers, and seals, this being referred
to below as "inventive use".
[0022] Additional subject matter of the invention will become
apparent from the description.
ADVANTAGES
[0023] In the light of the prior art it was surprising and
unforeseeable for the skilled worker that the object on which the
present invention was based could be achieved by means of the
slurries of the invention, the process of the invention, and the
inventive use.
[0024] In particular it was surprising that the slurries of the
invention were preparable easily and with very good
reproducibility.
[0025] In the absence of actinic radiation the slurries of the
invention were particularly stable on storage and exhibited no
propensity to settle and/or agglomerate. Nevertheless, where there
was any slight sedimentation and/or agglomeration of particles (A)
after a prolonged period, the sedimented particles (A) were rapidly
redispersible by brief stirring and the agglomerated particles (A)
could be comminuted rapidly again.
[0026] The slurries of the invention gave coatings of the
invention, especially clearcoats of the invention, which had
outstanding appearance properties, in particular a high gloss. They
were particularly resistant to chemicals, condensation, and
mechanical exposure, in particular that from stone chipping.
Furthermore, they were highly scratch resistant. Moreover, they
effectively leveled unevennesses in the substrate, which otherwise
showed through to the topmost coating of a multicoat paint system,
and therefore they had a particularly smooth and defect-free
surface. In particular, however, they remained free from pops and
mud cracking even at particularly high film thicknesses of more
than 80 .mu.m.
DETAILED DESCRIPTION OF THE INVENTION
[0027] The slurry of the invention is entirely or substantially
free from organic solvents.
[0028] "Substantially free" means that the slurry of the invention
in question has a solvent content <10%, preferably in each case
<5%, and in particular <2% by weight.
[0029] "Entirely free from" means that the solvent content is in
each case below the customary, known detection limits for organic
solvents.
[0030] The slurry of the invention is structurally viscous.
[0031] The viscosity behavior referred to as "structurally viscous"
describes a state which takes account, on the one hand, of the
needs of application and also, on the other hand, of the
requirements in terms of storage stability and settling stability
of the slurry of the invention: In the mobile state, such as when
the slurry of the invention is being pumped around in the circuit
of a coating plant, for example, and during application, the slurry
of the invention adopts a low-viscosity state which ensures good
processing properties. In the absence of shearing stress, in
contrast, the viscosity increases and hence ensures that the slurry
of the invention already on the substrate to be coated exhibits a
reduced tendency to sag on vertical surfaces ("curtaining"). In the
same way, the higher viscosity in the immobile state, such as
during storage, for instance, means that settling of the solid
particles (A) is very largely prevented or ensures that, in the
event of any slight settling and/or agglomeration during the
storage period, the slurry of the invention can be re-established
by agitation.
[0032] The structurally viscous behavior is set preferably by means
of suitable thickeners (A2), especially nonionic and ionic
thickeners (A2), which are preferably in the aqueous phase (B).
[0033] For the structurally viscous behavior it is preferred to set
a viscosity range of 50 to 1500 mPas at a shear rate of 1000
s.sup.-1 and of 150 to 8000 mPas at a shear rate of 10 s.sup.-1 and
also of 180 to 12 000 mPas at a shear rate of 1 s.sup.-1.
[0034] The slurry of the invention comprises as its disperse phase
solid and/or highly viscous, dimensionally stable particles
(A).
[0035] "Dimensionally stable" means that, under the customary,
known conditions of the storage and application of structurally
viscous, aqueous powder dispersions, the particles (A) exhibit only
slight agglomeration and/or breakdown into smaller particles, if
any at all, but instead substantially or entirely preserve their
original form even under the influence of shearing forces.
[0036] The particles (A) have a z-mean average particle size as
measured by photon correlation spectroscopy of 80 to 750 nm,
preferably 80 to 600 nm, and in particular 80 to 400 nm.
[0037] Photon correlation spectroscopy is a customary, known method
of measuring dispersed particles having sizes <1 .mu.m. The
measurement can be conducted, for example, by means of the
Malvern.RTM. Zetasizer 1000.
[0038] The particle size distribution can be adjusted in any
desired way. The particle size distribution results preferably from
the use of suitable wetting agents (A2).
[0039] The amount of particles (A) in the slurry of the invention
may vary very widely and is guided by the requirements of the case
in hand.
[0040] Preferably the amount is 5% to 70%, more preferably 10% to
60%, very preferably 15% to 50%, and in particular 15% to 40% by
weight, based on the slurry of the invention.
[0041] The particles (A) comprise at least one, especially one,
free-radically crosslinkable binder (A1) having [0042] a glass
transition temperature of -70 to +50.degree. C., preferably -60 to
+20.degree. C., and in particular -60 to +10.degree. C., [0043] an
olefinically unsaturated double bond content of 2 to 10 eq/kg,
preferably 2 to 8 eq/kg, more preferably 2.1 to 6 eq/kg, very
preferably 2.2 to 6 eq/kg, with very particular preference 2.3 to 5
eq/kg, and in particular 2.5 to 5 eq/kg of the binder (A1), and
[0044] an acid group content of 0.05 to 15 eq/kg, preferably 0.08
to 10 eq/kg, more preferably 0.1 to 8 eq/kg, very preferably 0.15
to 5 eq/kg, with very particular preference 0.18 to 3 eq/kg, and in
particular 0.2 to 2 eq/kg of the binder (A1).
[0045] The amount of acid groups is determined preferably via the
acid number in accordance with DIN EN ISO 3682.
[0046] The particles (A) contain the binders (A1) in an amount of
50% to 100%, preferably 55% to 100%, more preferably 60% to 99%,
very preferably 70% to 99%, and in particular 80% to 99% by weight,
based in each case on (A).
[0047] The particles (A) may therefore consist of the binder (A1).
With preference the particles (A) further comprise at least one of
the additives (A2) described below. The olefinically unsaturated
double bonds of the binder (A1) are preferably in groups selected
from the group consisting of (meth)acrylate, ethacrylate,
crotonate, cinnamate, vinyl ether, vinyl ester, dicyclopentadienyl,
norbornenyl, isoprenyl, isopropenyl, allyl or butenyl groups;
dicyclopentadienyl ether, norbornenyl ether, isoprenyl ether,
isopropenyl ether, allyl ether or butenyl ether groups; or
dicyclopentadienyl ester, norbornenyl ester, isoprenyl ester,
isopropenyl ester, allyl ester or butenyl ester groups, preferably
(meth)acrylate groups. In particular the olefinically unsaturated
double bonds are in acrylate groups.
[0048] The binders (A1) are oligomeric or polymeric.
[0049] "Oligomeric" means that the binder (A1) in question is
composed of 3 to 12 monomeric structural units.
[0050] "Polymeric" means that the binder (A1) in question is
composed of more than 8 monomeric structural units.
[0051] Whether a binder (A1) composed of 8 to 12 monomeric
structural units is regarded as being an oligomer or a polymer
depends primarily on its number-average molecular weight.
[0052] The number-average molecular weight of the binder (A1) may
vary very widely and is guided by the requirements of the case in
hand, in particular by the viscosity which is advantageous for the
processing and the use of the binder (A1). The viscosity of the
binder (A1), accordingly, is typically adjusted so that after the
slurry of the invention has been applied and the resulting wet film
dried, filming of the particles (A) is achieved easily and without
problems.
[0053] The number-average molecular weight is preferably 1000 to 50
000 daltons, more preferably 1500 to 40 000 daltons, and in
particular 2000 to 20 000.
[0054] The polydispersity of the molecular weight may likewise vary
very widely and is preferably 1 to 10, in particular 1.5 to 8.
[0055] Suitable binders (A1) include all oligomers and polymers
which have the profile of properties described above.
[0056] The binder (A1) is selected preferably from the group
consisting of oligomeric and polymeric epoxy(meth)acrylates,
urethane (meth)acrylates, and carbonate (meth)acrylates. Urethane
(meth)acrylates are used in particular.
[0057] The urethane (meth)acrylates (A1) are prepared by reacting
[0058] (a1) at least one compound containing at least two
isocyanate groups and selected from the group consisting of
aliphatic, aromatic or cycloaliphatic di- and polyisocyanates with
[0059] (a2) at least one compound having at least one, especially
one, isocyanate-reactive functional group, selected preferably from
the group consisting of hydroxyl groups, thiol groups, and primary
and secondary amino groups, especially hydroxyl groups, and at
least one, especially one, of the above-described groups which
contain a free-radically polymerizable olefinically unsaturated
double bond, preferably a (meth)acrylate group, in particular an
acrylate group, [0060] (a3) at least one compound having at least
one, especially one, isocyanate-reactive functional group and at
least one, especially one, acid group, selected preferably from the
group consisting of carboxylic, phosphonic, phosphinic, sulfonic,
and sulfinic acid groups, preferably carboxylic and sulfonic acid
groups, especially carboxylic acid groups, and also [0061] (a4) if
desired, at least one compound having at least two, especially two,
isocyanate-reactive functional groups.
[0062] Examples of suitable compounds (a1) are customary, known di-
and polyisocyanates having an isocyanate functionality of on
average 2 to 6, preferably 2 to 5, and in particular 2 to 4.
[0063] "Aliphatic" means that the isocyanate group in question is
linked to an aliphatic carbon atom.
[0064] "Cycloaliphatic" means that the isocyanate group in question
is linked to a cycloaliphatic carbon atom.
[0065] "Aromatic" means that the isocyanate group in question is
linked to an aromatic carbon atom.
[0066] Examples of suitable aliphatic diisocyanates (a1) are
aliphatic diisocyanates, such as tetramethylene diisocyanate,
pentamethylene diisocyanate, hexamethylene diisocyanate,
octamethylene diisocyanate, decamethylene diisocyanate,
dodecamethylene diisocyanate, tetradecamethylene diisocyanate,
derivatives of lysine diisocyanate, tetramethylxylylidene
diisocyanate, trimethylhexane diisocyanate or 1,3- or
1,4-bis(isocyanatomethyl)cyclohexane.
[0067] Examples of suitable cycloaliphatic diisocyanates (a1) are
1,4-, 1,3- or 1,2-diisocyanatocyclohexane, tetramethylcyclohexane
diisocyanate, bis(4'-isocyanatocyclohexyl)methane,
(4'-isocyanatocyclohexyl)(2'-isocyanatocyclohexyl)-methane,
2,2-bis(isocyanatocyclohexyl)propane,
2,2-(4'-isocyanatocyclohexyl)-(2'-isocyanatocyclohexyl)propane,
1-isocyanato-3,3,5-trimethyl-5-(isocyanatomethyl)-cyclohexane
(isophorone diisocyanate), 2,4- or
2,6-diisocyanato-1-methylcyclohexane or diisocyanates derived from
dimer fatty acids, such as are sold under the tradename DDI 1410 by
Henkel and described in patents WO 97/49745 and WO 97/49747, such
as 2-heptyl-3,4-bis(9-isocyanatononyl)-1-pentylcyclohexane.
[0068] Examples of suitable aromatic diisocyanates (a1) are 2,4- or
2,6-tolylidene diisocyanate or their isomer mixtures, m- or
p-xylylene diisocyanate, 2,4'- or 4,4'-diisocyanatodiphenylmethane
or their isomer mixtures, 1,3- or 1,4-phenylene diisocyanate,
1-chloro-2,4-phenylene diisocyanate, 1,5-naphthylene diisocyanate,
diphenylene 4,4'-diisocyanate,
4,4'-diisocyanato-3,3'-dimethylbiphenyl, 3-methyl-diphenylmethane
4,4'-diisocyanate, 1,4-diisocyanatobenzene or
4,4'-diisocyanato-diphenyl ether.
[0069] Preference is given to using aliphatic and cycloaliphatic
diisocyanates (a1), especially hexamethylene diisocyanate,
1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate
and/or di(isocyanatocyclohexyl)methane.
[0070] Examples of suitable polyisocyanates (a1) are triisocyanates
such as nonane triisocyanate (NTI) and also polyisocyanates (a1)
based on the above-described diisocyanates and triisocyanates (a1),
especially oligomers containing isocyanurate, biuret, allophanate,
iminooxadiazinedione, urethane, carbodiimide, urea, uretonimine
and/or uretdione groups. Examples of suitable such polyisocyanates
(a1), and processes for preparing them, are disclosed for example
in patents and patent applications CA 2,163,591 A 1, U.S. Pat. No.
4,419,513 A, U.S. Pat. No. 4,454,317 A, EP 0 646 608 A 1, U.S. Pat.
No. 4,801,675 A, EP 0 183 976 A 1, DE 40 15 155 A 1, EP 0 303 150 A
1, EP 0 496 208 A 1, EP 0 524 500 A 1, EP 0 566 037 A 1, U.S. Pat.
No. 5,258,482 A, U.S. Pat. No. 5,290,902 A, EP 0 649 806 A 1, DE 42
29 183 A 1 or EP 0 531 820 A 1.
[0071] Preference is given to using the oligomers (a1) of
hexamethylene diisocyanate and of isophorone diisocyanate.
[0072] Examples of suitable compounds (a2) are the monoesters of
[0073] (a21) diols and polyols containing preferably 2 to 20 carbon
atoms and at least 2 hydroxyl groups in the molecule, such as
ethylene glycol, diethylene glycol, triethylene glycol,
1,2-propylene glycol, 1,3-propylene glycol,
1,1-dimethyl-1,2-ethanediol, dipropylene glycol, tripropylene
glycol, tetraethylene glycol, pentaethylene glycol, 1,4-butanediol,
1,5-pentanediol, neopentyl glycol, 1,6-hexanediol,
2-methyl-1,5-pentanediol, 2-ethyl-1,4-butanediol,
1,4-dimethyl-olcyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane,
glycerol, trimethylolethane, trimethylolpropane, pentaerythritol,
dipentaerythritol, ditrimethylolpropane, erythritol, sorbitol,
polytetrahydrofuran having an average molecular weight of 162 to
2000, poly-1,3-propanediol having an average molecular weight of
134 to 400 or polyethylene glycol having a molecular weight of
between 150 and 500, especially ethylene glycol; with [0074] (a22)
alpha,beta-unsaturated carboxylic acids, such as acrylic acid,
methacrylic acid, crotonic acid, itaconic acid, fumaric acid,
maleic acid, acrylamidoglycolic acid, and methacrylamidoglycolic
acid, especially acrylic acid.
[0075] Further examples of suitable compounds (a2) are the
monovinyl ethers of the above-described diols and polyols
(a21).
[0076] Further examples of suitable compounds (a2) are the
monoesters or monoamides of the above-described
alpha,beta-unsaturated carboxylic acids (a22) with [0077] (a23)
amino alcohols, such as 2-aminoethanol, 2-(methylamino)ethanol,
3-amino-1-propanol, 1-amino-2-propanol or 2-(2-aminoethoxy)ethanol,
[0078] (a24) thioalcohols, such as 2-mercaptoethanol, or [0079]
(a25) polyamines, such as ethylenediamine or
diethylenetriamine.
[0080] In particular, 2-hydroxyethyl acrylate is used.
[0081] Examples of suitable compounds (a3) are [0082] (a31) hydroxy
carboxylic acids, such as hydroxyacetic acid (glycolic acid), 2- or
3-hydroxypropionic acid, 3- or 4-hydroxybutyric acid,
hydroxypivalic acid, 6-hydroxycaproic acid, citric acid, malic
acid, tartaric acid, 2,3-dihydroxypropionic acid (glyceric acid),
dimethylolpropionic acid, dimethylolbutyric acid, trimethylolacetic
acid, salicylic acid, 3- or 4-hydroxybenzoic acid or 2-, 3- or
4-hydroxycinnamic acid, [0083] (a32) amino acids, such as
6-aminocaproic acid, aminoacetic acid (glycine), 2-aminopropionic
acid (alanine), 3-aminopropionic acid (beta-alanine) or the other
essential amino acids; N,N-bis(2-hydroxyethyl)glycine,
N-[bis(hydroxymethyl)-methyl]glycine or imidodiacetic acid, [0084]
(a33) sugar acids, such as gluconic acid, glucaric acid, glucuronic
acid, galacturonic acid or mucic acid (galactaric acid), [0085]
(a34) thiol carboxylic acids, such as mercaptoacetic acid, or
[0086] (a35) sulfonic acids, such as 2-aminoethanesulfonic acid
(taurine), aminomethanesulfonic acid, 3-aminopropanesulfonic acid,
2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid,
3-[4-(2-hydroxyethyl)piperazinyl]propanesulfonic acid,
N-[tris(hydroxymethyl)methyl]-2-aminoethanesulfonic acid,
N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,
5-sulfosalicylic acid, 8-hydroxyquinoline-5-sulfonic acid,
phenol-4-sulfonic acid or sulfanilic acid.
[0087] In particular, hydroxyacetic acid (glycolic acid) (a31) is
used.
[0088] The acid groups may be in ionized form.
[0089] Examples of suitable counterions are lithium, sodium,
potassium, rubidium, cesium, magnesium, strontium, barium or
ammonium ions and also primary, secondary, tertiary or quaternary
ammonium ions deriving from customary, known organic amines.
[0090] Examples of suitable compounds (a4) are the above-described
diols and polyols (a21), amino alcohols (a23), thioalcohols (a24)
or polyamines (a25).
[0091] The urethane (meth)acrylates (A1) are preferably prepared by
reacting compounds (a1), (a2) and (a3) and also, if desired, (a4)
with one another in a molar ratio such that for 3 equivalent
isocyanate groups from the compound (a1) there are [0092] 0.5 to 3,
preferably 0.8 to 2.5, more preferably 1.0 to 2.2, and in
particular 1.4 to 1.8 equivalents of isocyanate-reactive functional
groups from compound (a2) and [0093] 0.001 to 1.5, preferably 0.005
to 1.0, more preferably 0.01 to 0.8, and in particular 0.1 to 0.5
equivalents of isocyanate reactive functional groups from the
compound (a3), and, if desired, [0094] 0 to 2, preferably 0.1 to
1.8, more preferably 0.5 to 1.5, and in particular 0.8 to 1.3
equivalents of isocyanate-reactive functional groups from the
compound (a4).
[0095] Viewed in terms of method the preparation of the urethane
(meth)acrylates (A1) has no peculiarities but instead takes place
under the customary, known conditions of the reaction of
polyisocyanates in the absence of water at temperatures of 5 to
100.degree. C. In order to inhibit polymerization of the
olefinically unsaturated double bonds it is preferred to operate
under an oxygenous gas, in particular under air or air/nitrogen
mixtures.
[0096] The slurry of the invention is composed of at least one
disperse phase (A) and a continuous aqueous phase (B). In the
simplest case the disperse phase (A) is composed of the binder (A1)
and the continuous phase (B) is composed of water. Preferably,
however, the slurry of the invention further comprises at least one
customary, known additive (A2) in customary, known amounts.
[0097] Depending on its physicochemical properties an additive (A2)
may be in the disperse phase (A), i.e., the dimensionally stable
particles (A); alternatively, it may also form a separate disperse
phase (A2), such as a pigment, for example. In addition it may be
exclusively in the aqueous phase (B), such as a water-soluble salt,
for example, or may accumulate at the interface between aqueous
phase (B) and disperse phase (A), such as a wetting agent, for
example. It is possible not least for the additive (A2) to
partition itself between the disperse phase (A) and the aqueous
phase (B), such as a molecularly dispersely dissolved organic dye,
for example. The skilled worker therefore has the capacity to
predict, simply, how an additive (A2) will behave in the slurry of
the invention.
[0098] The additive (A2) is preferably selected from the group
consisting of salts which can be decomposed thermally without, or
substantially without, residue; binders other than the binders (B)
and curable physically, thermally and/or with actinic radiation;
neutralizing agents; thermally curable reactive diluents; reactive
diluents curable with actinic radiation; opaque and transparent,
color and/or effect pigments; molecularly dispersely soluble dyes;
opaque and transparent fillers; nanoparticles; light stabilizers;
antioxidants; devolatilizers; wetting agents; emulsifiers; slip
additives; polymerization inhibitors; free-radical polymerization
initiators, especially photoinitiators; thermolabile free-radical
initiators; adhesion promoters; flow control agents; film-forming
assistants; rheological assistants, such as thickeners and
structurally viscous sag control agents, SCAs; flame retardants;
corrosion inhibitors; free-flow aids; waxes; siccatives; biocides;
and matting agents.
[0099] With preference the slurry of the invention comprises salts
which can be decomposed thermally without, or substantially
without, residue, light stabilizers, wetting agents, emulsifiers,
flow control agents, photoinitiators, and rheological assistants as
additives (A2).
[0100] If it is to be used as a clearcoat slurry the slurry of the
invention preferably contains no opaque constituents, in particular
no opaque pigments or fillers.
[0101] Examples of suitable additives (A2) are known from German
patent applications [0102] DE 101 26 649 A1, page 16, paragraph
[0145], to page 18, paragraph [0189], [0103] DE 100 27 270 A1, page
11, paragraphs [0106] and [0107], or [0104] DE 101 35 997 A1, page
3, paragraph [0022], to page 4, paragraph [0033], and page 4,
paragraphs [0039] and [0040], page 10, paragraphs [0092] to
[0101].
[0105] Where the slurry of the invention includes thermally curable
constituents they are present in the dimensionally stable particles
(A) preferably in an amount <40%, more preferably <30%, and
in particular <20% by weight.
[0106] The slurry of the invention is prepared preferably by the
secondary dispersion process known from German patent application
DE 199 08 013 A 1, German patent DE 198 41 842 C 2 or German patent
application DE 100 55 464 A 1.
[0107] In that process the ionically stabilizable binders (A1) and
also, if desired, the additives (A2) are dissolved in organic
solvents, particularly water-miscible solvents which are highly
volatile. The resulting solutions are dispersed with the aid of
neutralizing agents (A2) in water. Dilution then takes place with
water, accompanied by stirring. The initial product is a
water-in-oil emulsion, which on further dilution undergoes
inversion to give an oil-in-water emulsion. This inversion point is
generally reached at solids contents of <50% by weight, based on
the emulsion, and can be recognized externally from a relatively
sharp drop in viscosity in the course of dilution.
[0108] The oil-in-water emulsion can also be prepared directly by
the melt emulsification of the binders (A1) and also, where
appropriate, of the additives (A2) in water.
[0109] It is of advantage in this context if the wetting agents
(A2) are added to the organic solution and/or to the water before
or during emulsification. Preferably they are added to the organic
solution.
[0110] The emulsion thus obtained, which still contains solvents,
is subsequently freed from solvents by means of azeotropic
distillation.
[0111] In accordance with the invention it is of advantage if the
solvents to be removed are distilled off at a distillation
temperature below 70.degree. C., preferably below 50.degree. C.,
and in particular below 40.degree. C. Where appropriate the
distillation pressure in this case is chosen such that in the case
of relatively high-boiling solvents the temperature is maintained
within this range.
[0112] In the simplest case the azeotropic distillation can be
brought about by stirring the emulsion at room temperature in the
open vessel for a number of days. In the preferred case the
solvent-containing emulsion is freed from the solvents by means of
vacuum distillation.
[0113] In order to avoid high viscosities, the quantity of water
and solvents removed by evaporation or distillation is replaced by
water. The water can be added before, after or else during the
evaporation or distillation, and can be added in portions.
Following the loss of solvents there is a rise in the glass
transition temperature of the dispersed dimensionally stable
particles, and instead of the previous solvent-containing emulsion
the structurally viscous aqueous dispersion (B) is formed, i.e.,
the slurry (A) of the invention.
[0114] Where appropriate the dimensionally stable particles are
mechanically comminuted in the wet state, an operation also
referred to as wet grinding. In this context it is preferred to
employ conditions such that the temperature of the material for
grinding does not exceed 70.degree. C., more preferably 60.degree.
C., and in particular 50.degree. C. The specific energy input
during the grinding operation is preferably 10 to 1000, more
preferably 15 to 750, and in particular 20 to 500 Wh/g.
[0115] Wet grinding can be carried out employing any of a very wide
variety of apparatus, which generate high or low shearfields.
[0116] Examples of suitable apparatus generating low shear fields
are customary, known stirred tanks, slot homogenizers,
microfluidizers or dissolvers.
[0117] Examples of suitable apparatus generating high shear fields
are customary, known agitator mills or inline dissolvers.
[0118] Particular preference is given to employing apparatus which
generate high shear fields. Of these apparatus, the agitator mills
are particularly advantageous in accordance with the invention and
are therefore used with very particular preference.
[0119] In the case of wet grinding, generally speaking, the slurry
of the invention is supplied to the above-described apparatus with
the aid of suitable devices, such as pumps, especially gear pumps,
and is circulated via said apparatus until the desired particle
size has been reached.
[0120] The slurry of the invention is preferably filtered before
being used. This is done using the customary, known filtration
equipment and filters. The mesh size of the filters may vary widely
and is guided primarily by the particle size and particle size
distribution. The skilled worker is therefore able easily to
determine the appropriate filters on the basis of this physical
parameter. Examples of suitable filters are monofilament flat
filters or bag filters. They are available on the market under the
brand names Pong.RTM. or Cuno.RTM..
[0121] The slurry of the invention can be applied outstandingly by
means of the customary, known methods of applying liquid coating
materials, such as injecting, spraying, knife coating, spreading,
pouring, dipping, trickling or rolling, for example. Preference is
given to employing spray application methods. It is preferred to
exclude actinic radiation during application.
[0122] Following its application, the slurry of the invention dries
without problems and exhibits filming at the processing
temperature, generally at room temperature. In other words, the
slurry of the invention, applied as a wet film, loses water when
flashed off at room temperature or slightly elevated temperatures,
with the particles present therein changing their original form and
coalescing to form a homogeneous film (A). Alternatively the
applied slurry of the invention may dry in powder form.
[0123] Drying can be accelerated through the use of a gaseous,
liquid and/or solid, hot medium, such as hot air, heated oil or
heated rolls, or of microwave radiation, infrared light and/or near
infrared (NIR) light. Preferably the wet film is dried in a
forced-air oven at 23 to 150.degree. C., more preferably 30 to
120.degree. C., and in particular 50 to 100.degree. C.
[0124] Thereafter the dried film (A) of the invention is cured by
free-radical polymerization.
[0125] The free-radical polymerization may be initiated and
maintained thermally. In that case it is preferred to use the
above-described apparatus and techniques. In certain cases it may
be of advantage to allow the flow procedure and the curing or
crosslinking reaction to proceed with a temporal offset, by running
a staged heating program or a so-called heating ramp. The
crosslinking temperature is preferably between 120 and 160.degree.
C. The corresponding bake time is between 10 and 60 minutes.
[0126] The free-radical polymerization is initiated and maintained
preferably with actinic radiation, more preferably with electron
beams or UV radiation, preferably UV radiation, especially UV-A
radiation.
[0127] In terms of method the actinic radiation cure has no special
features but may instead be carried out by means of the customary,
known apparatus and techniques, as are described for example in
German patent application DE 198 18 735 A 1, column 10, lines 31 to
61, German patent application DE 102 02 565 A1, page 9, paragraph
[0092], to page 10, paragraph [0106], German patent application DE
103 16 890 A1, page 17, paragraphs [0128] to [0130], international
patent application WO 94/11123, page 2, line 35, to page 3, line 6,
page 3, lines 10 to 15, and page 8, lines 1 to 14, or the U.S. Pat.
No. 6,743,466 B2, column 6, line 53, to column 7, line 14.
[0128] It is preferred to combine actinic radiation curing with
thermal curing.
[0129] On account of the advantageous properties of the slurry of
the invention and of the cured materials of the invention produced
from it, the slurry of the invention and the materials of the
invention can be employed with an extraordinary breadth. With
preference they are used as coating materials, adhesives, and
sealants for producing coatings, adhesive layers, and seals of the
invention.
[0130] The coatings, adhesive layers, and seals of the invention
may serve for coating, bonding, and sealing any of a very wide
variety of coated and uncoated substrates.
[0131] The substrates are preferably composed of metals, plastics,
wood, ceramic, stone, textile, fiber composites, leather, glass,
glass fibers, glass wool and rock wool, mineral-bound and
resin-bound building materials, such as plasterboard and cement
slabs or roofing shingles, and also composites of these
materials.
[0132] Substrates in question are preferably [0133] means of land,
water or air transport which are operated by muscle power, hot air
or wind, such as cycles, railroad trolleys, rowboats, sailboats,
hot air balloons, gas balloons or sailplanes, and also parts
thereof, [0134] motorized means of land, water or air transport,
such as motorcycles, utility vehicles or motor vehicles, especially
automobiles, watergoing or underwater craft or aircraft, and also
parts thereof, [0135] stationary floating bodies, such as buoys or
parts of harbor installations, [0136] the interior and exterior of
buildings, [0137] doors, windows, furniture, and [0138] hollow
glassware, [0139] small industrial parts, such as nuts, bolts, hub
caps or wheel rims, [0140] containers, such as coils, freight
containers or packaging, [0141] electrical components, such as
electronic windings, coils for example, [0142] optical components,
[0143] mechanical components, and [0144] white goods, such as
household appliances, boilers, and radiators.
[0145] In particular the substrates are automobile bodies and parts
thereof.
[0146] With preference the slurry of the invention is used for
producing the coatings of the invention.
[0147] The slurry of the invention can be used with particular
advantage as a primer, priming material, surfacer, basecoat,
solid-color top coat or clearcoat material for producing
single-coat or multicoat primer coating systems, corrosion control
coats, antistonechip priming coats, surfacer coats, basecoats,
solid-color topcoats or clearcoats.
[0148] With very particular advantage the slurry of the invention
is used for producing clearcoats as part of multicoat color and/or
effect paint systems, which are produced in particular by the
customary, known wet-on-wet techniques (cf. German patent
application DE 100 27 292 A1, page 13, paragraph [0109], to page
14, paragraph [0118]) from basecoat materials and the slurry of the
invention.
[0149] On account of their particular advantages the slurry of the
invention and the clearcoats of the invention produced from it are
outstandingly suitable for the OEM finishing of automobiles and for
the refinishing of automotive finishes, especially top-class
automobile finishes. The refinish can be done over a small area, as
a spot repair for example, or over a large area, either on the line
at the automakers plant, as an end-of-line repair for example, or
else in the paintshop.
[0150] Refinishing may be preceded by pretreatment of the damaged
surfaces in the region of the sites that are to be repaired. This
can be accomplished, for example, by partially dissolving the
surface with an organic solvent, smoothing, sanding, corona
treatment or flame treatment. It is a particular advantage of the
slurry of the invention that in many cases such pretreatments can
be omitted.
[0151] The multicoat color and/or effect paint systems of the
invention comprising at least one clearcoat of the invention meet
all of the requirements which are imposed on automotive finishes
(cf. European patent EP 0 352 298 B1, page 15, line 42, to page 17,
line 40) and in terms of their appearance correspond fully to a
Class A surface. In particular they are particularly smooth, free
even at high film thicknesses from paint defects such as craters or
cracks, and are resistant to weathering, to chemicals, to
condensation, to stone chipping, and to scratching.
EXAMPLES
Preparation Example 1
The Preparation of a Binder (A1)
[0152] Isopropenylidenedicyclohexanol was coarsely dispersed in
hydroxyethyl acrylate at 60.degree. C. with stirring. Added to this
suspension were the polyisocyanates, pentaerythritol
tri/tetra-acrylate, hydroquinone monomethyl ether,
1,6-di-tert-butyl-p-cresol, and methyl ethyl ketone. After
dibutyltin dilaurate had been added the reaction mixture became
hotter. It was stirred at 75.degree. C. for a number of hours until
the free isocyanate group content was constant. Then glycolic acid
and methanol were added and the mixture was stirred until free
isocyanate groups were no longer detectable.
[0153] The hydroxyl-containing compounds and the polyisocyanates
were used in amounts such as to give the equivalents ratios listed
below:
TABLE-US-00001 Isopropenylidenedicyclohexanol 33.7 eq OH
2-Hydroxyethyl acrylate 24.7 eq OH Pentaerythritol
tri/tetraacrylate 24.7 eq OH (average OH number: 100 to 111 mg
KOH/g) Basonat .RTM. HI 100 from BASF AG 56.25 eq NCO Allophanate
of hexamethylene 18.75 eq NCO diisocyanate and 2-hydroxyethyl
acrylate in accordance with international patent application WO
00/39183 Desmodur .RTM. W from Bayer AG 25 eq NCO Hydroquinone
monomethyl ether 0.05% by weight based on solids
1,6-Di-tert-butyl-p-cresol 0.1% by weight based on solids Methyl
ethyl ketone corresponding to a solids content of 70% by weight
Dibutyltin dilaurate 0.02% by weight based on solids Glycolic acid
6.8 eq OH Methanol 10.1 eq OH
[0154] The resulting binder (A1) had a glass transition temperature
of 2.5.degree. C., a viscosity at 23.degree. C. of 2.0 Pas, an
olefinically unsaturated double bond content of 3.12 eq/kg solids,
and an acid number of 11.41 mg KOH/g solids. It was outstandingly
suitable for preparing clearcoat slurries.
Example 1
The Preparation of a Clearcoat Slurry
[0155] 738.165 parts by weight of the solution of the binder (A1)
from Preparation Example 1, 10.438 parts by weight of a 50 percent
strength solution of Tinuvin.RTM. CGL 052 (light stabilizer from
Ciba Specialty Chemicals, containing one triazine group and two
cyclic, sterically hindered amino ether groups) in methyl ethyl
ketone, 9.185 parts by weight of Tinuvin.RTM. 400 (light stabilizer
from Ciba Specialty Chemicals), 7.228 parts by weight of
Lutensol.RTM. AT 50 (wetting agent from BASF AG), 8.246 parts by
weight of trimethylamine, 20.876 parts by weight of a
photoinitiator mixture of Irgacure.RTM. 184 from Ciba Specialty
Chemicals and Lucirin.RTM. TPO from BASF AG (weight ratio 5:1) were
mixed with one another. The resulting mixture was dispersed in 1004
parts by weight of deionized water. 0.117 part by weight of
ammonium acetate was added to this dispersion. The degree of
neutralization of the binder (B1) was 75%. The dispersion was
subsequently filtered through a 1 .mu.m Cuno.RTM. white filter.
[0156] The filtered dispersion was stirred in an open vessel at
room temperature for 24 hours so that the methyl ethyl ketone
evaporated.
[0157] The solvent-free dispersion was made up with 0.788 part by
weight of Baysilone.RTM. A13468 (flow control agent from Borchers)
and 15.776 parts by weight of Acrysol.RTM. RM-8W (nonionic
associative thickener from Rohm & Haas).
[0158] The z-mean average particle size of the resulting clearcoat
slurry was measured by means of photon correlation spectroscopy
(Malvern Zetasizer.RTM. 1000); it was 140 nm.
[0159] The clearcoat slurry had a solids content of 36.2% by
weight. It was outstandingly suitable for producing multicoat color
and/or effect paint systems for automobiles.
Example 2
The Production of Multicoat Color Paint Systems
[0160] The multicoat color paint systems were produced using steel
test panels which had been coated with a customary, known,
cathodically deposited, and baked electrocoat. Atop the
electrocoats in each case was applied a film of a customary, known
water-based surfacer from BASF Coatings AG and a film of a
customary, known, black aqueous basecoat material from BASF
Coatings AG, both films being applied wet-on-wet. Following their
application the films were each subjected to initial drying at
80.degree. C. for 10 minutes.
[0161] Subsequently the clearcoat slurry of Example 1 was applied
in wedge form to the dried basecoat film, so that drying of the
resulting clearcoat film and joint curing of the surfacer film,
basecoat film, and clearcoat film resulted in a wedge-shaped
clearcoat with a thickness of 10 to 100 .mu.m. Curing itself was
accomplished thermally at 155.degree. C. for 15 minutes and with UV
radiation in a dose of 1.5 J/cm.sup.2 (iron-doped mercury vapor
lamp from IST) under an oxygen-depleted atmosphere (1% by volume
oxygen). Even at a film thickness >80 .mu.m the clearcoat was
free from craters, mud cracking and microdefects ("starry
sky").
[0162] Additionally, atop the dried basecoat film, the clearcoat
slurry of Example 1 was applied in a uniform thickness, so that
drying of the resulting clearcoat film and joint curing of the
surfacer film, basecoat film, and clearcoat film resulted in a
clearcoat having a film thickness of 40 .mu.m. Here again, curing
itself took place thermally at 155.degree. C. in a forced-air oven
for 15 minutes and with UV radiation in a dose of 1.5 J/cm.sup.2
(iron-doped mercury vapor lamp from IST) under an oxygen-depleted
atmosphere (1% by volume oxygen).
[0163] The resultant black multicoat paint systems were
particularly highly bright, glossy, chemical resistant, stonechip
resistant, hard, flexible, scratch resistant, and condensation
resistant, as could be underscored by means of the experimental
results below:
Chemical Resistance:
TABLE-US-00002 [0164] DaimlerChrysler Gradient Oven Test Test
substance visible damage from Sulfuric acid: 44.degree. C. NaOH:
48.degree. C. Tree resin: >75.degree. C. Deionized water:
>75.degree. C.
Condensation:
TABLE-US-00003 [0165] Constant Conditions Test (CC 240 h) Degree of
blistering: 0 Size: 0 Notes: slight swelling, slight blushing
Cross-cut test with adhesive GT-1 tape removal:
Hardness:
TABLE-US-00004 [0166] Fischerscope Penetration Hardness: Universal
hardness: 137.4 N/mm.sup.2 at 25.6 mN average depth of penetration:
2.66 .mu.m relative elastic resilience: 64.5% Creep at 25.6 mN:
10.74% Creep at 0.4 mN: 33.64%
Stone Chipping:
TABLE-US-00005 [0167] VDA: Index: 1.5 Rusting: 0.5 Ball impact:
satisfactory
Scratch Resistance:
TABLE-US-00006 [0168] Amtec-Kistler laboratory wash unit: Initial
gloss (20.degree.): 89 units Residual gloss without cleaning: 65
units Residual gloss after cleaning: 71 units Residual gloss: 81%
Sand test (cf. German patent application DE 198 39 453 A1, page 9,
lines 1 to 63): Residual gloss: 84%
* * * * *